Discharge apparatus



Dec. 2, 1941. F. H. GULLIKSEN 2,254,695

DISCHARGE APPARATUS Filed Sept. 3, 1938 p 44 a 4/ fix g E; 2. 43

Trans. [mg Ca .fm 3 200- p P g V /50 Q I G /00 47 5. ge 6'0 0 l l I l 00/ 02 0.3 04 0.5 WITNESSES: Dans. Imp. INVENTOR m fi/MW pimp f7/7/7 /7.Gu/ll/rse/z ATTORNEY Patenl'ed Dec. 2,

UNITED STATES PATENT OFFICE DISCHARGE APPARATUS Pennsylvania ApplicationSeptember 3, 1938, Serial No. 228,329

9 Claims.

form are obtained by interposing a saturable transformer between thesupply source and the point at which the impulses are impressed. Withthe primary of the saturable transformers connected directly across thesource, the peaked impulses derived from the secondary occur at pointsin the half waves of the source displaced by 90 from the zero potentialpoints. A shift in the phase of the peaked potential relative to thesource waves is attained in accordance with the teachings of the priorart of which I am aware, by connecting a variable resistor in serieswith the primary of the transformer. As the series resistance increases,the angle of shift is increased. With this arrangement, however,

the maximum phase shift attainable is some- 1? what less than 90 and,therefore, it has no utility in the numerous situations in which a shiftgreater than 90 is desirable. Another disadvantage of the device arisesfrom the fact that as the resistance is increased, the amplitude of thepeaked potential derived in the secondary of the transformer decreasesso that for a substantial shift in phase the secondary potential isrelatively small and as a matter of fact, does not have the desiredpeaked wave form.

It is accordingly an object of my invention to provide an arrangementfor driving, from a source of periodically pulsating potential,potentials of short duration compared to the periods of the source whichmay be shifted in phase with 4 reference to the Waves of the source by asubstantial angle.

Another object of my invention is to provide apparatus for deriving,from a source of alternating potential, impulses of short durationcompared to the half-periods of the source which shall occur at pointsin the half waves of the source that may be selected at will over anangle substantially greater than 90.

Another object of my invention is to provide apparatus for deriving,from a source of periodically pulsating potential, potential impulses ofshort duration compared to the periods of the source, which shall havesubstantially a uniform amplitude regardless of the phase anglev betweenthe impulses and the maxima of the waves of the source.

More specifically stated, it is an object of my invention to provideapparatus of simple and inexpensive structure for attaining potentialsof peaked wave form to control an electric discharge valve.

According to my invention, a capacitor is connected in parallel with thevariable resistor in the primary circuit of the saturable transformer. Ihave found that when the capacitor has the maximum capacity permitted bythe rating of the transformer, the phase of the potential derived fromthe secondary of the transformer may be shifted over an extensive anglerelative to the waves of the source, and when a shift is introduced, thederived potential does not vary substantially in amplitude.

While in the preferred practice of my invention the control transformeris saturable, I do not intend to limit its scope only to apparatusincorporating transformers of this type. Where the teaching of myinvention is used with an ordinary non-saturabie transformer, it isintended that such use shall constitute an equivalent within its scope.It is further to be noted that while in the specific practice of myinvention disclosed herein the variable resistor and the capacitor areconnected to the primary winding of the transformer, these impedancesmay also be connected to an auxiliary winding. Such connection, whenmade for the purpose of attaining the same results attained by myinvention, is intended to be included within the scope of my invention.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment when read in connection with the accompanying drawing, inwhich:

Figure 1 is a diagrammatic View showing an embodiment of my invention;

Fig. 2 is a graph showing certain results attained with apparatusconstructed in accordance with my invention; and

Fig. 3 is another graph showing further results attained with theapparatus.

The apparatus shown in Figure 1 comprises an electric discharge valve 5preferably, but not necessarily, of the arc-like type. The valve has ananode l, a hot cathode 9 and a control elecvalve 5 from a saturabletransformer 2| which is supplied with potential through anothersecondary section 23 of the supply transformer ll.

The saturable transformer 2| is of the usual structure having asaturable core 25 on the wide leg 21 of which the primary 29 is wound,while the secondary 3| is wound on the narrow leg 33. The secondary 3|of the transformer 2| is connected between the control electrode II andthe cathode 9 through a biasing source 35. The impulses impressedbetween the control electrode H and the cathode 9 when the primary 29 ofthe transformer 2| is energized counteract the effect of the biasingsource 35 and render the valve 5 conductive.

To shift at will the phase of the points in the half-waves of the source|3 at which the impulses occur, a rheostat 3! is connected in serieswith the primary 29 of the saturable transformer 2: and a capacitor 39is connected in parallel with the resistor. I have found that the mostsatisfactory results ar attained when the capacitor 39 has the highestpossible impedance permitted by the rating of the saturable transformer2|. The value of the maximum impedance maybe derived from the simpleconsideration that for the maximum current flow the inequality XcXz. Xr.must be satisfied. In this inequality, X0 is the capacity impedance andXL is the impedance of the saturable transformer 2|. From the aboverelationship it is seen that the minimum capacity impedance is given bythe expression This relationship is Well borne out by experiments whichI have carried out.

The tests were made with an impulse transformer 2| having a primaryreactance of 247 ohms and a rated primary current of .45 ampere. Thetransformer was supplied through various rheostats 31 and capacitors 39from a SO-cycle source |3 of the ordinary commercial type. The plots inFigs. 2 and 3 are graphs showing the results of the tests.

In Fig. 2 the ratio of the amplitude of the peak potential actuallyattained to the maximum peak potential attained when the resistance 37in series with the primary 29 of the saturable transformer 2| is zero,is plotted vertically and the ratio of the transformer impedance to thecapacity imis plotted horizontally. The upper curve M shows the resultsobtained for a resistance 3! of 1,000 ohms and the lower curve 43 showsthe results for a resistance of 2,000 ohms. It will be noted that as theratio of th transformer impedance to the capacity impedance approaches/2, the ratio plotted a ordinate approaches 1. That is to say, when theratio of the impedances is substantially one-half, the variation in theamplitude of the peaked potential derived from the secondary 3| is aminimum. The condition which exists in the absence of a capacitor 39 isrepresented by the points of intersection of the curves 4| and 43 andthe axis of ordinates M. These points show that with the capacitorabsent, the amplitude of the peaked potentials is reduced to less thanA; of its maximum value when the resistance is 2,000 ohms and to of itsmaximum value with 1,000 ohms resistance.

In Fig. 3 the angle over which the phase of the peaked potentialrelative to the half-waves of the source l3 may be shifted is plottedvertically and the ratio of the impedances 37 and 39 is plottedhorizontally. The upper curve 45 corresponds to a 10,000 ohms variableresistor 3'! and the lower curve 41 to a 2,000 ohms resistor. In thiscase it will be noted again that an angl of shift of 180 may be attainedby selecting the ratio to be approximately 0.5. Attention is called tothe fact that for the ratio of zero, that is to say,'for a situation inwhich the capacitor is entirely absent, the angle of shift isapproximately 60 for the 2,000 ohms resistor and for the 10,000 ohmsresistor.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

I claim as my invention:

1. For use in converting the pulsations of a source of periodicallypulsating potential into pulses of short duration compared to a periodof the source displaced in phase relative to the pulsaticns of thesource by an angle which is predeterminable at will, the combinationcomprising a saturable transformer having primary winding means incircuit with said source, and secondary winding means, and variableresistance means shunted by capacitative means in circuit with one ofsaid winding means.

2. For use in converting the pulsations of a source of periodicallypulsating potential into pulses of short duration compared to a periodof the source displaced in phase relative to the pulsations of thesource by an angle which is predeterminable at will, the combinationcomprising a saturable transformer having primary winding means incircuit with said source, and secondary winding means, and variableresistance means shunted by capacitative means in circuit with saidprimary winding means.

3. For use in converting the pulsations of a source of periodicallypulsating potential into pulses of short duration compared to a periodof the source displaced in phase relative to the pulsations of thesource by an angle which is predeterminable at will, the combinationcomprising a saturable transformer having primary winding means incircuit with said source, and secondary winding means, and variableresistance means shunted by capacitative means in circuit with saidprimary winding means, said capacitative means having a reactance ratiowith said transformer of the order of l to 2.

4. For use in converting the pulsations of a source of periodicallypulsating potential into pulses of short duration compared to a periodof the source displaced in phase relative to the pulsations of thesource by an angle which is predeterminable at will, the combinationcomprising a saturable transformer having primary winding means incircuit with said, source, and

secondary winding means, and variable resistance means shunted bycapacitative means in circuit with said primary winding means, saidcapacitative means having a value such'th'at &

approaches one-half, where XL is the transformer reactance, at thefrequency of said source and X is the reactance of said capacitativemeans at said frequency.

5. In combination, an electric discharge device havin a controlelectrode and a plurality of principal electrodes, a saturabletransformer having primary and secondary windings, a source ofperiodically pulsating potential, means for connecting the secondary ofsaid transformer between said control electrode and one of saidprincipal electrodes, and means for connecting the primary of saidtransformer to said source, the last said connecting means includingvariable resistance means and capacity means connected in parallel withsaid resistance means.

6. In combination, an electric discharge device having a controlelectrode and a plurality of principal electrodes, a saturabletransformer having primary and secondary windings, a source ofperiodically pulsating potential, means for impressing a potential fromsaid source between said principal electrodes, means for connecting thesecondary of said transformer between said control electrode and one ofsaid principal electrodes, and means for connecting the primary of saidtransformer to said source, the last said connecting means includingvariable resistance means and capacity means connected in parallel withsaid resistance means.

7. In combination, an electric discharge device having a controlelectrode and a plurality of principal electrodes, a saturabletransformer having primary and secondary windings, a source ofperiodically pulsating potential, means for connecting the secondary ofsaid transformer between said control electrode and one of saidprincipal electrodes, and means for connecting the primary of saidtransformer to said source, the last said connecting means includingvariable resistance means and capacity means connected in parallel withsaid resistance means, said capacity means having a reactance ratio withsaid transformer of the order of 1 to 2.

8. In combination, an electric discharge device having a controlelectrode and a plurality of rincipal electrodes, a saturabletransformer having primary and secondary windings, a source ofalternating potential, means for connecting the secondary of saidtransformer between said control electrode and one of said principalelectrodes, and means for connecting the primary of said transformer tosaid source, the last said connecting means including variableresistance means and capacity means connected in parallel with saidresistance means.

9, In combination, an electric discharge device of the arc-like typehaving a control electrode and a plurality of principal electrodes, asaturable transformer having primary and secondary windings, a source ofperiodically pulsating potential, means for connecting the secondary ofsaid transformer between said control electrode and one of saidprincipal electrodes, and means for connecting the primary of saidtransformer to said source, the last said connecting means includingvariable resistance means and capacity means connected in parallel withsaid resistance means.

FINN H. GULIKSEN.

